a(1) = 1; for n > 1, a(n) = sigma(sum of the previous terms) where sigma(k) = sum of the divisors of k.

A165929

a(1) = 1; for n > 1, a(n) = sigma(sum of the previous terms) where sigma(k) = sum of the divisors of k.

Terms

    a(0) =1a(1) =1a(2) =3a(3) =6a(4) =12a(5) =24a(6) =48a(7) =120a(8) =264a(9) =480a(10) =1104a(11) =2064a(12) =4128a(13) =10752a(14) =19320a(15) =38328a(16) =91992a(17) =170016a(18) =369600a(19) =745560a(20) =1854720a(21) =3845760a(22) =7765296a(23) =14990520a(24) =29910120a(25) =59856720a(26) =119710416a(27) =298755600a(28) =667297320a(29) =1446528360

External references